1. Field of the Invention
The present invention generally relates to hydrokinetic torque coupling devices, and more particularly to a hydrokinetic torque coupling device with a torsional vibration damper.
2. Description of the Prior Art
An internal combustion engine exhibits irregularities due to the succession of combustion events in the engine cylinders. Torsion damping devices allow these irregularities to be filtered before the drive torque is transmitted to an automotive transmission. This is because the vibrations must be damped before they enter the transmission and produce unacceptably troublesome noise. To accomplish this, it is known to interpose a torsion damping device between a drive shaft and a transmission (or driven) shaft. The torsion damping device is generally arranged in a hydrokinetic torque coupling device that allows temporary rotational connection of the drive shaft to the transmission shaft.
Typically, a hydrokinetic torque coupling device includes a hydrodynamic torque converter and a torsion damping device positioned between an axially oriented coaxial drive shaft and driven shaft of the automotive transmission. The torsion damping device includes a torque input element and a torque output element, and circumferentially acting elastic members. The circumferentially acting elastic members are interposed between the torque input element and the torque output element. In so-called “long travel” damping devices, the elastic members are mounted, in groups of at least two elastic members, in series between the input element and output element.
A torque converter of this kind typically has a rotating casing that is capable of transmitting drive torque to the damping device by means of a friction locking clutch, traditionally called a lock-up clutch. The torque converter also has a turbine wheel mounted rotatably inside the casing.
For some applications, the torsion damping device may also include a pendulum oscillator conventionally utilized both in friction clutches and in motor vehicle hydrokinetic coupling apparatuses. A pendulum oscillator has at least one pendulum mass or flyweight, generally several, that is arranged around the rotation axis of the engine shaft and is free to oscillate around a notional axis substantially parallel to the rotation axis of the engine shaft. When the masses of a pendulum oscillator react to rotational inconsistencies, they move in such a way that a center of gravity of each of the pendulum masses oscillates around an axis substantially parallel to the rotation axis of the engine shaft. The radial position of the center of gravity of each pendulum mass with respect to the rotation axis of the engine shaft, as well as the distance of the center of gravity with respect to the notional oscillation axis, are established so that in response to centrifugal forces, the oscillation frequency of each of the pendulum masses is proportional to the rotation speed of the engine shaft.
While hydrokinetic torque coupling devices and torsion damping devices, including but not limited to that discussed above, have proven to be acceptable for vehicular driveline applications and conditions, improvements that may enhance their performance and cost are possible.